Another Sinorogomphus, but not very different

While visiting the mountains along the Laotian border close to Da Nang in the first week of May I caught a Sinorogomphus that looked very similar to S. sachiyoae. But the lateral pattern on S2 was somewhat different and upon close inspection the shape of the tips of the superior appendages was also different, if not a lot. I thought it had to be S. sachiyoae, but after consultation of the literature it turned out to be a species described already in 1969 by Asahina: Sinorogomphus vietnamensis. A nice and interesting addition to my list. In fact I observed the species in Quang Tri, Quang Nam and Thua Thien - Hue Provinces.

Male Sinorogomphus vietnamensis. Note the pattern on S2 and the fact that the superior appendages seem to touch the inferiors.

The female is even more like S. sachiyoae.

In dorsal view the appendages are quite similar

But in lateral view the tip of the superior appendage is longer and bends downward towards the epiproct.